1. Field of the Invention
The present invention relates to a negative type resist which has a good sensitivity with respect to deep ultraviolet (UV) light having a wavelength of from 180 to 350 nm and, also, relates to a method for producing a negative type resist pattern on a substrate by using this resist.
2. Description of the Prior Art
It is known that photolithography employing ultraviolet light having a wavelength of from 350 nm to 450 nm is heretofore used as a method for forming a circuit pattern of, for example, a semiconductor integrated circuit. As the formation of highly dense element patterns on substrates is required in the art, fine detail patterns having a limiting width of less than 2 or 3 microns have been desired. As a result, lithography using an electron beam or an X-ray beam was proposed in order to fulfill the needs of microfabrication .
However, lithography using an electron beam or an X-ray beam has drawbacks in that the circuit and the mechanism for deflecting the electron or X-ray beam are complicated.
The use of deep UV light having a wavelength of from 180 to 350 nm, in lieu of UV light, in lithography was proposed in 1975 by Burn Jeng Lin (See: J. Vac. Sci. Technol., Vol 12, No. 6, November/December 1975, pages 1317-1320). He reported that a fine detail pattern of 1 micron or less was able to be easily obtained by using optical structures used in conventional photolithography.
As negative type photoresists used in the deep UV lithography, an allylated or allyl substituted copoly (maleic anhydride-fluoroalkylvinyl ether), 2,3-dibromopropyl acrylate and the like have been proposed. However, these negative type photoresists have drawbacks in that (1) the resolving power thereof is poor, (2) the correct exposure thereof is largely affected by an irradiation atmosphere and (3) the storage stability thereof is poor.